Alkaline chromium-contaminated soil solidifying, stabilizing and repairing method

Abstract

The invention relates to an alkaline chromium-contaminated soil solidifying, stabilizing and repairing method, and belongs to the technical field of environmental engineering. Hexavalent chromium in chromium-contaminated soil is separated into water by adopting water-washing pretreatment; hexavalent chromium-contaminated water is adjusted to be acid by adopting sulfuric acid as an acidifying or alkalizing agent, therefore, a reduction reaction of hexavalent chromium is facilitated, sulfuric acid can participate in a later curing reaction, and high-valued application of sulfuric acid is achieved; the efficiency of reducing hexavalent chromium in the contaminated water into trivalent chromium is improved by adopting CaS5 as a reducing agent, and water-washed soil and water after the reduction treatment are mixed for solidification and stabilization treatment; resource utilization of blast furnace slag is achieved by adopting the blast furnace slag and active magnesium oxide as solidification materials, enhancing of the strength of the solidified soil and wrapping of contaminants can be quickly achieved, and the long-term stability of the treated chromium-contaminated soil is good. The method has the advantages of being low in treatment cost, good in effect, free of secondary pollution, convenient to operate, good in long-term stability, high in resource utilization and the like.

Description

technical field [0001] The invention belongs to the technical field of environmental engineering, and in particular relates to a method for stabilizing alkaline chromium-contaminated soil. Background technique [0002] At present, there are more than 20 sites left over from the shutdown of chromium salt factories, more than 40 sites for storing chromium slag left over from history, sites of thousands of electroplating (chrome plating) companies, and sites of hundreds of tanning companies in China. However, only a few small-scale sites in China have carried out soil pollution control work, and the pollution status of typical sites is very serious, and chromium-contaminated sites not only pollute soil, but also pollute groundwater. With the acceleration of urbanization and industrialization, more and more land is polluted by chromium, and the strategic layout of cities is readjusted. A large number of chromium-polluted sites are in urgent need of treatment. Soil chromium poll...

AI Technical Summary

Problems solved by technology

[0005] The application of Chinese Patent Publication No. CN102228901A adopts adding ferrous salt solution to chromium-contaminated soil to reduce hexavalent chromium to trivalent chromium, and then add lime solution to convert trivalent chromium into chromium hydroxide. The main problem is that the treatment effect is not good. Good, poor long-term stability, etc.

[0006] The application of Chinese Patent Publication No. CN201310493630.2 adopts the method of adding iron powder or sodium metabisulfite or a mixture of the two under acidic conditions to rinse the chromium pollution, which has the problems of serious secondary pollution, poor treatment effect and high cost.

[0007] The application of Chinese Patent Publication No. CN201210355258.4 uses microbial methods to repair the soil. There are mainly steps such as long fermentation period, certain requirements for initial concentration, and activation and cultivation of bacteria. The operation is relatively complicated and is not suitable for large-scale Applications

However, there are few studies on the solidification and stabilization methods of chromium-contaminated soils. Due to the strong migration of hexavalent chromium, the general solidification and stabilization methods have poor applicability.

At the same time, the existing chromium-contaminated soil treatment technology is relatively backward, resulting in low restoration efficiency, high cost, secondary pollution and environmental risks of chromium-contaminated soil